We studied deposits belonging to the Bihor Unit from the Northern Apuseni Mountains (Romania). The described outcrops are located in the SW of Șes Mountain and the northeastern Pădurea Craiului Massif. We determined the depositional environment and the mechanisms controlling the accumulation of Upper Triassic–Lower Jurassic continental deposits. The sedimentary formations contain carbonate breccia and calcretes embedded in continental clay deposits. Late Triassic–Early Jurassic depositional processes were influenced by the inherited paleobasement of the subaerially exposed Middle Triassic deposits. Numerous fragments of Anisian and Ladinian carbonate deposits are encased in weathered clay deposits accumulated on karstification surfaces developed at the top of Middle Triassic limestones. We integrated facies analysis and clay mineralogy to obtain an accurate interpretation of the continental processes acting at the Triassic–Jurassic boundary in the northern part of the Apuseni Mountains. The composition of the carbonate pebbles is described in terms of the carbonate facies, whereas the clay mineralogy was determined by applying X-ray powder diffraction. Thirteen facies associations are described consisting of carbonate, siliciclastic and ferilitic rock types. Such facies indicate sediment accumulation in a continental, mixed carbonate-siliciclastic depositional environment. A Late Triassic exposure event was followed by an Early Jurassic (Hettangian) transgression. Two major facies types are identified on the basis of their depositional environment. The first category includes subaerially exposed Triassic carbonates and ferilitic facies, while the second category consists of transgressive siliciclastic facies from the basal Lower Jurassic (Hettangian) sediments. The existing data suggest continental deposition in alternating, arid–humid warm climate conditions at the Triassic–Jurassic transition.

我们研究了来自北部Apuseni山（罗马尼亚）的Bihor单元的沉积物。所描述的露头位于Șes Mountain的西南部和东北的PădureaCraiului地块。我们确定了沉积环境和控制上三叠纪—下侏罗纪大陆沉积物堆积的机制。沉积岩层包含埋在大陆粘土沉积物中的碳酸盐角砾岩和碎屑。三叠纪晚期-侏罗纪早期的沉积过程受地下三叠纪中部沉积物的继承古成岩作用的影响。在中三叠纪石灰岩顶部发育的岩溶化表面上堆积的风化粘土沉积物中包裹着大量的Anisian和Ladinian碳酸盐矿床碎片。我们将相分析和粘土矿物学相结合，以获得对在Apuseni山北部的三叠纪—侏罗纪边界作用的大陆过程的准确解释。碳酸盐卵石的组成是根据碳酸盐相来描述的，而粘土矿物学是通过应用X射线粉末衍射来确定的。描述了由碳酸盐，硅质碎屑和铁素体岩石类型组成的十三种相联系。这些相表明沉积物在大陆性碳酸盐-硅质碎屑混合沉积环境中聚集。三叠纪晚期暴发事件之后是侏罗纪早期（Hettangian）海侵事件。根据其沉积环境确定了两种主要的相类型。第一类包括地下暴露的三叠纪碳酸盐岩和铁素体相，第二类包括来自下侏罗统（Hettangian）沉积物的海侵硅质碎屑相。现有数据表明，在三叠纪-侏罗纪过渡期，干旱-潮湿交替的温暖气候条件下存在大陆沉积。